The present invention relates to the field of electric submersible pump assemblies and associated support equipment, and more particularly but not by way of limitation, to a dual gearbox electric submersible pump assembly utilized with various pumps including progressive cavity pumps.
In oil wells and the like from which the production of fluids is desired, a variety of fluid lifting systems have been used to pump the fluids to surface holding and processing facilities. It is common to employ various types of downhole pumping systems to pump the subterranean formation fluids to surface collection equipment for transport to processing locations.
One such prior art pumping system is a submersible pumping assembly which is supported in the wellbore, the submersible pumping assembly having a pump and a motor to drive the pump to pressurize and pass the fluid through production tubing to a surface location. A typical electric submersible pump assembly includes a submersible pump and an electric motor with a gearbox. The purpose of the gearbox is to allow the motor to operate under different loads by controlling the torque.
Prior art gearboxes have not proved effective in handling the requirements of many pumps including the progressive cavity pump (PCP). Thus, there is a need for a gearbox capable of effectively controlling various pumps including progressive cavity pumps in applications that are currently limited by the torque capacity of the reduction gearbox.
The present invention provides an electric submersible pump assembly for producing fluid from a production zone to a surface. The electric submersible pump assembly includes an electric submersible motor, a progressive cavity pump and a second pump. The progressive cavity pump is disposed above a lower packer and includes a section head and intake tubing to receive the fluid from the production zone. The second pump is disposed below an upper packer and includes production tubing and an intake section to receive the fluid from the progressive cavity pump. A first motor interface connects the electric submersible motor to the progressive cavity pump and a second motor interface connects the electric submersible motor to the second pump. The first and second motor interfaces include a gearbox, a flex shaft and a seal section.
The electric submersible pump assembly includes an inlet pump having a section head such that the fluid enters from the production zone through the inlet pump, an outlet pump having an intake section such that the fluid enters from the inlet pump and is discharged through the outlet pump, an electric submersible motor, a first motor interface that connects the electric submersible motor to the inlet pump, and a second motor interface that connects the electric submersible motor to the outlet pump; each motor interface having a gearbox that connects to the electric submersible motor, a pump shaft connector that connects to the pump, and a seal section that joins the pump shaft connector to the gearbox.